Process of making photosensitizing-dyes effective for infra-red radiation



i No Drawing.

; strArEs PATENT ora ion.

ELLIOT o. ADAMS, or BERKELEY, eALIroImIanNn LOUIS E. WISE, or New Yonx,N. Y.

rnoenss or MAKING- rnorosnnsmrzme-nyns EFFECTIVE non. mum-nan YRADIATION.

(FILED ummr. TEE ACT or union 3, 1883, 22 STAT. L., 525.

To all whom it may concern: J

Be. it known that we ELLIOT Q. AoAMs and LoUIs E. Wrsn, citizens of theUnited States of America, and employees of the Department ofAgriculture, residing in the cityof. Berkeley, county of-Alameda, Stateof California, and in the city of New York,

county of estchester, State of New York, respectively, (whosepost-oflice addresses are Department of Agriculture, Washington, D. C.,)haveinvented new and useful Improvements in the Processes of MakingPhotosensitizing-Dyes Effective for Infra- Red Radiation, of which thefollowing is a specification. i

Dyes of this type are known to be substituted ammonium salts, thesensitizing action being due tothe positive ammonium radical.

Hence the nature of the negative radical will be of influence only in sofar as it affects adversely the solubility ofthe compound or possessesdeleterious action of its own. .It will therefore be possible to use anyquater nary compounds satisfactory in these respects.

This application is made under the act of March 3, 1883, chapter 143 (22Stat. L. 625), and the invention herein described and claimed may beused by the Government of the- United States or any of its oflicers oremployees in the rosecution of work for the Government, an any personin. the United States, without payment to us of any royalty thereon.

We have found that these dyes can be obtained directly in a state ofsuflicient purity by the action of air and of sodium methylate inabsolute methyl alcoholic solution upon the quaternary halid or otheraddition products of a, -dimethylated quinolin bases.

, By a, -dimethylated quinolin bases are meant such derivatives ofquinolin and related bases as have methyl groups both ad.- jacent anddiametrically opposite the nitrogen of the heterocyclic ring.

The same products can be obtained,

though less satisfactorily, by the use of other alkalis 'in dilutedmethyl alcoholic, in

' brilliant green prismatic crystalsis obtained,

ethyl alcoholic or in aqueous solution.

he following examples will serve to illustrate the preferred procedure.The invention, however, is'not confined to these exam les. The parts areby weight.

Patented Apr. 27, 1920.

xample 1 6.54 parts of 2, 4, G-trimethyl quinolin ethiodid are dissolvedin-8 parts of cold absolute methyl alcohol and a solution of sodiummethylate, prepared by dissolving 0.23 part metallic sodium in 16 par-tsabhe use of an impure intermediate leads to the simultaneous formationof d es of the cyanin and isocyanin types, whic may be detected in aspectroscopic examination of the solution by the cyanin and isocyanin 1absorption maxima near 6000 and 5600 A.

U., respectively. The pure material gives an absorption maximum near6600 A.

Example 2: 6.26 parts of 2, 4-dimethyl quinolin ethiodid are dissolvedin 64: parts absolute methyl alcoholand very gradually added to asolution of 3.4 parts of silver nitrate in 80 parts of hot absolutemethyl alcohol. The precipitate is.filtered off by suction. The filtrateis concentrated to half its original volume and cooled to 10 C. A.

solution of sodium'methylate prepared by dissolving 0.23 part metallicsodium in 16 parts absolute methyl alcohol is added and the mixtureallowed to stand in a vessel exposed toair for 24 hours. 'No crystalsare formed during this period, but dye formation is indicated by theintense blue-green color of the solution. The mixture is then raduallyconcentrated at room temperature In a partially exhausted dessicator.over calcium chlorid for 48 hours. A crop of from which the motherliquor may be siby cautious further concentration of the mother liquors.

The dyes obtained as described in the examples above are sensitive toheat rays and should be stored in a cool dry place.

Having now fully described our invention, what we claim and desire toprotect by Letters Patent is'-- q 1. The process of producing infra-redphotographic sensitizing dyes by the interaction of-air and of sodiummethylate in absolute methyl alcoholic solution with the quaternaryhalid addition-products of a, Y: dimethylated quinolin derivatives.

2. The process of producing infra-red photographic sensitizing dyes bythe interaction of air and of sodium methylate in absolute methylalcoholic solution with the quaternary addition products ofsay-dimethylated quinolin derivatives;

In testimony whereof, we aflix our signatures in the presence of twosubscribing'witness'es.

ELLIOT Q. ADAMS. LOUIS E. WISE. Witnesses: J

LOUIS-A. MIKES A, HERBERT L. J. HALL R, I

